Screw-type anchor

ABSTRACT

A self-tapping masonry anchor includes an axial bore that is formed at one end and extends through a portion of the anchor.

BACKGROUND OF THE INVENTION

[0001] Self-tapping masonry anchors are known in the art. One example ofa self-tapping masonry anchor is disclosed in U.S. Pat. No. 4,973,210.This anchor has a cutting shaft 6 with an externally threaded fasteningportion 5 (or a fastening portion 10 having an internally-threaded bore11) and a cutting portion 6 having a raised external helix 7. The anchoris secured in a masonry hole by first forming a hole in the masonry andthen driving the cutting portion 6 into the hole using an oscillatoryrotating hammer blows. A key may be driven into a longitudinal slot 12passing through the concrete, masonry or brickwork along a line ofinterruption in the raised helix embedded in the hole which is said toprevent the fastening from rotating or from being removed from the hole.

[0002] It would be desirable to have a self-tapping masonry anchor inwhich the anchor is securable in masonry by releasable engagement with atool received within a bore of the anchor such that the tool may beeasily removed from the bore after inserting the anchor in the masonry.It would also be desirable to have an anchor in which the externalcutting thread is disposed within close proximity of the portion of theanchor in which an axial bore extends so that the anchor has arelatively short longitudinal extent, is securable in a relativelyshallow hole and/or is secured with its exposed end flush with, orrecessed within a masonry hole.

SUMMARY OF THE INVENTION

[0003] The above needs are met, and the shortcomings of prior art areovercome by the anchor of the invention. According to one embodiment,the anchor includes a helical thread of the type suited for tappingmasonry, the thread extending from a first end to a first intermediatestation disposed between the first and a second end of the anchor, anaxial bore adapted for releasably engaging an anchor inserting tool, thebore being formed at the second end, extending into the anchor andterminating at a second intermediate station that is one ofapproximately coincident with the first intermediate station and betweenthe first intermediate station and the first end. In this embodiment,the anchor may include a second engagement formed on the wall of thebore, the second engagement being disposed between the tool engagementand the second end and the tool engagement may correspond to a hex-typeengagement.

[0004] In another embodiment, a method for forming a self-tappingmasonry anchor from a cylindrical blank includes the steps of forming anaxial bore extending from a first end and terminating at a firstintermediate station disposed between the first end and a second end,and forming a thread by rolling, the thread extending from the secondend to a second intermediate station, the second intermediate stationbeing one of approximately coincident with the first intermediatestation and between the first intermediate station and the first end.The bore may be cold forged, and the piece may be tapped by a coldrolling process.

[0005] In another embodiment, a method for inserting a self tappingmasonry anchor in a masonry hole includes the steps of driving theanchor into the masonry hole until a second, exposed end is one ofapproximately flush with the hole opening and disposed below the holeopening, and then removing the tool from the bore. In this embodiment, atool is inserted into a bore and engaged with the bore walls. The pieceis then driven into the hole and then removed by pulling the toolstraight out of the bore. Such a tool engagement may correspond to afemale-hex.

[0006] In another embodiment, an anchor for coupling a mountingstructure to masonry includes a solid portion that extends from a firstend of the anchor and terminates at an intermediate station locatedbetween the first and a second end of the anchor, a hollow portiondefined by an axial bore extending from the second end to theintermediate station, wherein a first bore portion defines a toolengagement for releasably engaging an anchor inserting tool, a secondbore portion for releasably securing a structure to the anchor, and ahelical thread of the type suited for tapping masonry, the threadextending over a length that is no less than approximately thelongitudinal extent of the solid portion.

[0007] Additional features and advantages of the invention will be setforth or be apparent from the description that follows. The features andadvantages of the invention will be realized and attained by thestructures and methods particularly pointed out in the writtendescription and claims hereof as well as the appended drawings.

[0008] It is to be understood that both the foregoing generaldescription and the following detailed description are exemplary andexplanatory and are intended to provide further explanation withoutlimiting the scope of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

[0009] The accompanying drawings, which are included to provide afurther understanding of the invention, are incorporated in andconstitute a part of this specification, illustrate preferredembodiments of the invention and together with the description serve toexplain the principles of the invention. In the drawings:

[0010]FIG. 1 is a planar view of a first embodiment of a self-tappingmasonry anchor made in accordance with the principles of the invention.

[0011]FIG. 2 is top view of the anchor of FIG. 1.

[0012]FIG. 3 is a planar cross-section view of the anchor of FIG. 1,taken at section III-III of FIG. 2.

[0013]FIG. 4 is a planar view of the anchor of FIG. 1 embedded inmasonry.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Anchors according to the invention will now be described indetail with frequent reference to preferred embodiments, such as anchor10 illustrated in FIGS. 1-4. The invention is concerned withself-tapping masonry anchors that are securable in a pre-bored masonryhole. Once secured in the hole, the anchor may then be used to supportstructure, such as a pipe hanger, utility tray, ducts, lighting system,sprinkler system, electrical system, drop ceiling or refrigerationsystem. The anchor may be secured in a masonry hole of varying depth ordiameter, have a varying length threading and may be formed toaccommodate common fasteners for attaching structure, e.g., threadedfasteners, or even a custom fitting without departing from the scope ofinvention. In one embodiment, the exposed end of the anchor (i.e., theend that receives the mating structure) may be flush with the masonrysurface, as in the example illustrated in FIG. 4. In other embodiments,the anchor may be sunken into the masonry hole or extend out from thehole.

[0015] Referring now to a preferred embodiment illustrated in FIGS. 1-4,anchor 10 is formed from a generally cylindrical stock metal andincludes an external threaded portion 16 extending from a forward end 12of anchor 10. An upper portion 18 extends from threaded portion 16 tofastening end 14. Anchor 10 includes a solid portion 34 and a hollowportion 36 whose longitudinal extent is defined by the length of a bore20 extending from fastening end 14 towards forward end 12. Threadedportion 16 may extend over hollow portion 36, in addition to solidportion 34. Referring to FIGS. 2 and 3, bore 20 may be generallycircular and includes a tool fitting 24 at one end and a fixtureattachment 26, e.g., a helical thread 26 a, at the opposite end adjacentopening 28 of bore 20.

[0016] A camfer 30 may be formed at forward end 12 to assist withaligning anchor 10 with the masonry hole. Camfers 32 a, 32 b are alsopreferably formed at fastening end 14 and at the junction of threadedportion 16 and upper portion 18. Referring to FIG. 3, which illustratesa cross-sectional slice of anchor 10 taken at section III-III in FIG. 2,tool fitting 24 is preferably formed into tool engagement surfaces thatwill reliably sustain high localized stresses resulting from torquesapplied by an anchor inserting tool, e.g. an oscillatory rotatinghammer, hammer drill or impact wrench, as anchor 10 is driven into themasonry hole. In a preferred embodiment, tool fitting 24 corresponds toa female hex-type tool engagement, walls 24 a, 24 b, and 24 c of whichmay be formed as shown in FIG. 3. A hex-type fitting is preferred as itis a common type of tool engagement. In other embodiments, tool fitting24 may correspond to other types of engagements characterized by, e.g.,longitudinally extending, opposed planar walls of appropriate depth forreacting torques required to tap masonry. It is preferred to havelongitudinally extending so that the tool may be easily removed frombore 20 after anchor 10 is inserted into the masonry hole. In caseswhere, for example, tool fitting 24 is a helical thread, the tool maybecome locked in the bore. For this reason, it may be desirable to avoidusing a helical thread for tool fitting 24. But it is not consideredlimiting on the invention that a particular type of tool engagement isused over another.

[0017] Threaded portion 16 is of the type that is suitable forself-tapping masonry, as opposed to soft material (e.g., wood, plastic)or metal. Examples of thread patterns suited for tapping masonry aredescribed in U.S. Pat. No. 6,419,435 to Gaudron and U.S. Pat. No.5,957,6363 to Giannuzzi et al., the entire contents of which areincoporated by reference in their entirety for all purposes. In apreferred embodiment, threaded portion 16 includes a helical cuttingthread 38, land 40, preferably formed as an arcute, e.g., hemispherical,land, and a valley disposed between land 40 and cutting thread 38 anddefining a root diameter of the threading. As described in the abovereferences, as a self-tapping masonry anchor is driven into masonry, thedebris accumulated from cutting into this friable material compacts in acompaction zone disposed between success rows of the cutting thread.This compacted debris creates a frictional resistance between the anchorand the wall of the hole, which resists dislodgment of the anchor fromthe hole. Embodiments of the invention may have a hemishperical orplanar land disposed between valleys which may be defined by a rootdiameter. The land may have a diameter that is equal to, or slightlyless than the diameter of the hole so as to promote a frictionalresistance between the anchor and the hole wall. Other types of masonrythread patterns may alternatively be used in place of the thread designsdisclosed above. Accordingly, the invention is not limited to aparticular type, or variety of self-tapping masonry thread.

[0018] The cutting thread of the anchor, e.g., thread 38, may define amaximum diameter of the anchor, such as when the anchor is designed tobe driven into a constant diameter hole and the exposed end, e.g.,fastening end 14, is flush with, or disposed below the masonry surfacewhen the anchor is fully inserted into the hole. The maximum diameter ofupper portion 18 is preferably sized to be the same as, or slightly lessthan the diameter of the masonry hole so that fastening end 14 may bepositioned within the masonry surface. Land 40 may be sized to have amaximum diameter extent that is equal to, or slightly greater than themaximum diameter of upper portion 18.

[0019] Bore 20 preferably has a stepped diameter, with tool fitting 24having a diameter that is slightly less than than the outer diameter offixture attaching portion 26. A helical thread is preferably formedalong the wall surface of fixture attaching portion 26 for engagementwith a mating helical thread of the connecting structure. Other types offastener engagements may be used in place of a helical thread.

[0020] Referring to FIG. 4, anchor 10 is shown embedded in masonry 50and engaged with walls 54 defining a pre-formed hole. In this preferredembodiment, hole has a depth that allows fastening end 14 to bepositioned approximately flush with surface 52. Cutting thread 38 isengaged with walls 54 and the diameter of upper portion 18 isapproximately the same diameter as the hole.

[0021] A preferred method for forming an anchor according to theinvention uses cold forging. The steps include forming the bore of theanchor by drawing the piece using a punch press, followed by a secondtool that taps the outer surface using a rolling pin. The Fixtureattaching portion, e.g., a helical thread, is then formed along an innerwall of the bore.

[0022] Although the foregoing description is directed primarily topreferred embodiments of the invention, it is noted that othervariations and modifications will be apparent to those skilled in theart, and may be made without departing from the spirit or scope of theinvention.

We claim:
 1. An integrally formed, self tapping masonry anchor having alength extending between a first end and second end of the anchor, theanchor being insertable in a masonry hole using a tool, comprising: ahelical thread of the type suited for tapping masonry, the threadextending from the first end to a first intermediate station disposedbetween the first and second ends; an axial bore adapted for releasablyengaging an anchor inserting tool, the bore being formed at the secondend, extending into the anchor and terminating at a second intermediatestation that is one of approximately coincident with the firstintermediate station and between the first intermediate station and thefirst end.
 2. The anchor of claim 1, further including a fastnerengagement disposed between the tool engagement and the second end. 3.The anchor of claim 2, wherein the fastner engagement is formed on abore wall.
 4. The anchor of claim 1, wherein the second intermediatestation is between the first intermediate station and the first end andat least a substantial portion of a tool engagement, formed in the bore,is located between the first intermediate station and the first end. 5.The anchor of claim 1, further including a female hex for engaging thetool.
 6. A method for forming a self-tapping masonry anchor from acylindrical blank, the blank having a first and second end defining alongitudinal extent of the blank, comprising the steps of: forming anaxial bore extending from the first end and terminating at a firstintermediate station disposed between the first and second ends; andforming a thread by rolling, the thread extending from the second end toa second intermediate station, the second intermediate station being oneof approximately coincident with the first intermediate station andbetween the first intermediate station and the first end.
 7. The methodof claim 6, wherein the forming an axial bore step includes the step ofcold forging the axial bore.
 8. A method for inserting a self tappingmasonry anchor in a masonry hole having a hole opening, the masonryanchor having formed thereon a helical threading of the type suited fortapping masonry, the anchor having first and second ends defining thelongitudinal extent of the anchor, and an axial bore is formed in theanchor, comprising the steps of: engaging an anchor inserting tool withthe bore; driving the anchor into the masonry hole until the second endis one of approximately flush with the hole opening and disposed belowthe hole opening; and removing the tool from the bore including pullingthe tool out of the bore.
 9. The method of claim 8, wherein theenagaging step includes engaging the tool with at least a portion of thebore that is devoid of a helical thread.
 10. The method of claim 8,wherein the engaging step includes engaging a hex-shaped portion of thebore with the tool.
 11. The method of claim 8, further including thestep of attaching a structure to the anchor by engagement of a secondengagement of the anchor with a corresponding mating portion of thestructure.
 12. The method of claim 11, wherein the attaching a structurestep includes attaching the structure to a second engagement formed inthe bore.
 13. The method of claim 8, wherein the engaging step includesthe step of pushing the tool into locking engaging with the bore.
 14. Amasonry anchor that is embedded in a hole, comprising: a first anchorportion including a helical threading formed thereon, the thread beingembedded in a helical groove of the hole formed by the thread as theanchor is driven into the hole by the tool; and a second anchor portionextending from the first portion to a location that is one ofapproximately flush with and recessed within the masonry hole, thesecond portion having formed therein an axial bore including a pluralityof axially extending, opposed planar walls for releasably engaging atool.
 15. The anchor of claim 14, wherein the hole is preformed as ahole having a constant hole diameter, the helical threading has a threaddefining a major threading diameter, and the second anchor portion has aconstant outer diameter that is less than the major threading diameterand approximately equal to the hole diameter.
 16. The anchor of claim14, wherein the plurality of longitudinally extending, opposed planarwalls is a female hex.
 17. An anchor for coupling a mounting structureto masonry by engagement of a fastener of the mounting structure to theanchor, the anchor having first and second ends defining a longitudinalextent of the anchor, comprising: a solid portion extending from thefirst end and terminating at an intermediate station located between thefirst and second ends; a hollow portion defined by an axial boreextending from the second end to the intermediate station, wherein afirst bore portion defines a tool engagement for releasably engaging ananchor inserting tool, and a second bore portion for releasably securinga structure to the anchor; and a helical thread of the type suited fortapping masonry, the thread extending over a length that is no less thanapproximately the longitudinal extent of the solid portion.
 18. Theanchor of claim 17, wherein no more than approximately 30% of thelongitudinal extent of the anchor corresponds to the solid portion. 19.The anchor of claim 18, wherein the threading extends over at least 60%of the longitudinal extent of the anchor.
 20. The anchor of claim 17,wherein the helical thread is a forged helical thread.